A sloth moves at roughly two metres per minute. It almost never descends to the ground. When a highway cuts through its forest, it is effectively stranded — and a road crossing means almost certain death. Now, researchers across South America are quietly solving this problem with an elegant, low-tech solution: rope bridges strung through the canopy. And camera traps are confirming the animals are actually using them.
A Mongabay investigation published in early March 2026 documents the rapid spread of canopy bridge programmes across the Amazon and Atlantic forests, where economic development and infrastructure expansion are fragmenting habitats at pace. The results are offering genuine hope for some of the region's most vulnerable species.
**Why Tree-Dwelling Animals Are Especially Vulnerable**
Most wildlife crossing solutions — underpasses, culverts, even the grand wildlife overpasses now being built in North America — are designed for ground-dwelling animals. Deer, pumas, bears: they cross roads at ground level.
But for arboreal mammals like howler monkeys, spider monkeys, three-toed sloths, and South American porcupines, the ground is a foreign and dangerous place. These animals spend virtually their entire lives in the canopy. When roads cut through their forests, they face a stark and often fatal choice: risk the road, or stay isolated in an ever-shrinking patch of trees. Isolation leads to inbreeding, population collapse, and local extinction — even when the animals themselves appear healthy.
**The Bridge Revolution**
Canopy bridges — artificial structures made from thick ropes, nets, and wooden platforms, strung between trees at canopy height on either side of a road — offer these animals a safe passage that respects their biology.
In the Peruvian Amazon, biologists Justin Santiago and Lindsey Swierk deployed sophisticated bridge systems integrating multiple ropes and platforms at varying heights, designed to accommodate the different movement styles of different species. The camera trap footage they collected was striking: saki monkeys, sloths, and porcupines all using the bridges, often at night, often without any habituation period.
*"They just… used them. There was no conditioning, no training, no food lures. We put up the bridge and within days we had footage of animals crossing."* — Lindsey Swierk, Mongabay 2026
**More Than Just Crossing Roads**
The research is revealing that canopy bridges do more than reduce roadkill. By reconnecting fragmented forest patches, they allow animals to: - **Access new food sources** as seasons change or local supplies run out - **Find mates from other populations** — critical for genetic diversity in small, isolated groups - **Expand their territory** gradually as forest patches are restored - **Re-establish normal social behaviour** that isolation had disrupted
**Brazil Considers Making It National Policy**
Perhaps the most significant development is that Brazil's National Department of Transport Infrastructure is now studying the adoption of canopy bridge requirements as a national standard for road construction. If implemented, every new road project cutting through arboreal habitat would legally require wildlife crossing infrastructure at canopy height — a policy shift that could protect hundreds of species across millions of kilometres of new road development.
**The Simplicity Is the Point**
One of the most appealing aspects of canopy bridges is their cost-effectiveness. Unlike grand wildlife overpasses costing millions, a well-constructed canopy bridge can be installed for a fraction of the price, using locally sourced materials, and maintained by community rangers.
In a region where conservation budgets are often stretched thin and the scale of the challenge is immense, that scalability matters. A solution that works, is affordable, and can be replicated across thousands of road crossings is worth far more than a perfect solution deployed in only a handful of places.
The sloths, monkeys, and porcupines of the Amazon don't need much. They need their trees to be connected. Some ropes and platforms, strung with care across a highway, are proving to be enough. 🦥🐒
*Sources: Mongabay (March 4, 2026) · WWF · Animals Around the Globe · Brazil National Transport Infrastructure Department*
